20,222 research outputs found
Real trajectories in the semiclassical coherent state propagator
The semiclassical approximation to the coherent state propagator requires
complex classical trajectories in order to satisfy the associated boundary
conditions, but finding these trajectories in practice is a difficult task that
may compromise the applicability of the approximation. In this work several
approximations to the coherent state propagator are derived that make use only
of real trajectories, which are easier to handle and have a more direct
physical interpretation. It is verified in a particular example that these real
trajectories approximations may have excellent accuracy.Comment: 19 pages, 6 figure
Realizing the Potential of Marine Biotechnology : Challenges and Opportunities
A paid open access option is available for this journal. Author's final version or publisher's version/PDF Authors may deposit in funding agency designated repository after 12 monthsPeer reviewedPublisher PD
Schrodinger equation from an exact uncertainty principle
An exact uncertainty principle, formulated as the assumption that a classical
ensemble is subject to random momentum fluctuations of a strength which is
determined by and scales inversely with uncertainty in position, leads from the
classical equations of motion to the Schrodinger equation. Thus there is an
exact formulation of the uncertainty principle which precisely captures the
essence of what is "quantum" about quantum mechanics.Comment: Latex, 18pp, nature of fluctuations & differences from stochastic
mechanics clarifie
On two recent proposals for witnessing nonclassical gravity
Two very similar proposals have been made recently for witnessing
nonclassical features of gravity, by Bose et al. and by Marletto and Vedral.
However, while these proposals are asserted to be very general, they are in
fact based on a very strong claim: that quantum systems cannot become entangled
via a classical intermediary. We point out that the support provided for this
claim is only applicable to a very limited class of quantum-classical
interaction models, corresponding to Koopman-type dynamics. We show that the
claim is also valid for mean-field models, but that it is contradicted by
explicit counterexamples based on the configuration-ensemble model. Thus,
neither proposal provides a definitive test of nonclassical gravity.Comment: New references added, minor corrections. Close to final versio
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